The present invention relates to lamp monitors, and more particularly to motor vehicle lamp monitors.
Motor vehicles, and particularly buses, have several exterior lamps including stop, turn, tail, reverse and overhead lamps. The lamps may have different voltage and current requirements. Operation of the lamps is very important to the safety of the passengers and other vehicles. If a lamp or other lamp is not operating correctly, the operator of the motor vehicle should be made aware of the problem as soon as possible.
Previously, the operation of the lamps was sensed by a coil inductively coupled to the lamp circuit. If current flowed in the lamp circuit, the inductively coupled coil would illuminate a status lamp located near the driver. By visually inspecting the status lamp, the driver could determine if the particular lamp was operating.
Such an arrangement for status lamps was acceptable for incandescent lamps and other lamps. Lamps are now often made of LEDs (light emitting diodes). LED lamps offer several advantages over incandescent lamps, such as efficiency, improved life span, compactness, weight, and response time.
However, LED lamps often have a wide variety of operating currents. Thus, to use a system of coils to indicate operation of the LED lamps requires a specific coil for each type of LED lamp. Further, the life of an LED lamp is much longer than that of an incandescent lamp. The operational characteristics of the coil may significantly change over the life of an LED lamp, reducing the accuracy of the coil.
In addition, over the life of a vehicle, an incandescent lamp may be substituted for an LED lamp and vice versa.
Further, some buses have a combination of LED lamps and incandescent lamps. The current drawn by the LED lamps and the incandescent lamps differ, requiring different coils for the LED lamps and the incandescent lamps. Obviously, the maintenance of a number of different coils is problematic.
An improved lamp monitor and method for monitoring the status of the lamps is highly desirable.